Now, that map includes mercury concentrations in the tissue of fish in each lake – especially yellow perch and largemouth bass. Biologist Kirsten Nelson says wild freshwater fish like those build up mercury from other fish they eat.

“Basically the higher up the food chain you go, the more concentrated the mercury is likely to be,” she says.

The state already has guidelines on how much wild freshwater fish people should be eating in order to avoid mercury poisoning. It depends on species and where the fish were caught.

Officials say children and women who are or may become pregnant shouldn't eat any fish from certain water bodies or species due to mercury risks.

The toxic metal comes mainly from air pollution that blows into New Hampshire from Midwestern coal-fired power plants. But Nelson says those emissions – and coal use – are declining.

"And that will eventually show up in the fish we're eating,” she says.

The state would like to study that change more. But its data is patchy. It’s based mostly on fish that anglers donate – and those donations are at an all-time low.

Nelson says they'd welcome more – especially from places like Coos County, larger lakes like Winnipesaukee, and species with data to build on like bass and perch.

Last week, the Environmental Protection Agency said the Coakley Landfill, a superfund site in North Hampton, does not currently pose an unacceptable risk to human health.

That message came as a surprise to some members of a task force charged with investigating a cancer cluster on the Seacoast. They have been arguing for months that the EPA needs to be more proactive in addressing contamination at the site.

NHPR’s Seacoast Reporter Jason Moon recently sat down with All Things Considered host Sally Hirsh-Dickinson to talk more about this.

After pulling his first nominee for the position, Gov. Chris Sununu brought forward a new nomination to oversee the state’s environmental agency at Wednesday’s executive council meeting: Public Utilities Commissioner Robert Scott, of Bow.